Harnessing of energy from various renewable sources, including wind energy, wave energy, and ocean thermal energy includes the use of onshore and offshore wind energy and/or ocean-energy platforms to tap better wind/wave profiles for efficient clean energy production. The two main variations of ocean currents that typically interact to generate waves are tidal currents and marine currents. Water temperature differences in the ocean's water layers are mainly responsible for marine currents, while tidal currents are primary caused by the moon's gravitational effect on earth. Both currents are typically predictable, the tidal current, based on the moon's location relative to earth as it rotates around the earth, and earth's rotation that determines the marine currents.
Ocean waves typically carry anywhere between 8000-80,000 TWh/yr (Terawatt hour per year) of wave energy according to theoretical estimates, from all global ocean resources. However, certain areas, like in Europe for example, the actual technical electricity production may vary between 130 to above 1000 TWh/yr. Current estimate places that the average measurement of energy stored in ocean waves is about 10 to 50 KW (Kilowatt) for every meter height of the wave crests.
Improvements to turbine design in current wave energy converters is the key focus of most research over the past decade, including focus on one such turbine, the “wells turbine”. The wells turbine is a unidirectional flow turbine that rotates in a single direction irrespective of the wave direction. A key challenge with wave energy generators is that the ocean wave enters and exists with varying forces, at different velocities. Such devices as the oscillating water column (OWC) for ocean wave trapping methods is another focus of wave energy research, which has been progressing since the early 1980s. However, the OWC is limited to the capability of the turbine, which in turn has its limitations related to the state of the wave flow rate.
Further, better valve control methods contribute to improvements in the flow rate and air pressure from the incoming and exiting wave cycle. However, the valves provide irregular and non-linear flow rates as a result of the air flow turbulence generated when cross-sectional mismatch occurs in the chamber intake areas. Potential work is in progress in terms of location issues, for the wave energy trapping structures, in the interest of maximizing balance issues with wave thrust and captured potential. Balance of offshore structures is a focus of current research, where control methods maintain stability during the harnessing process, without substantial dampening of waves during harnessing and reasonable dampening of waves during stormy weather to protect the structure. Such control and absorption methods still face problems as a result of issues in the direction of attack presented by ocean waves, and the varying nature of weather cycles. Further, conventional systems are exposed to salt-water which corrodes most of the equipment and increases the need for continuous maintenance of a power generation system.